Deposition of particulate aerosol material in the lung has long been recognized as a source of disease and disability. Much is known of the aerodynamic behavior of spherical or nearly spherical particles under the viscous flow conditions often termed Stokes Settling. In recent years theoretical treatments for rod-shaped particles have been refined and experimental verification obtained. Lung deposition models have been developed which utilize this information to predict aerosol deposition patterns in the human respiratory tract. Unfortunately, little is known experimentally and practically nothing is available theoretically on the behavior of platelet, or flake, aerosols under the viscous flow conditions found in the small airways of the lung. The proposed research is designed to evaluate the behavior of platelet particles in viscous flow through fluid dynamic modeling, computer simulation, and through actual settling of a micron size orthotropic aerosol. This study represents a comprehensive approach to elucidating the aerodynamic characteristics of a class of particle shapes about which little is known. The results of this research will then be suitable for incorporation in new or existing aerosol lung deposition models.